What Happened to the Dinosaurs?

by William Silvert

Evolution

Many elaborate and sophisticated theories have been presented to explain why the dinosaurs became extinct. Most of these refer to environmental driving forces, such as gradual climate change (after all, the great extinction actually occurred over a period of millions of years) or catastrophic events associated with clouds of iridium released by collision with a comet (the Alvarez theory). However evolutionary theory offers a simple alternative.

Suppose that an island inhabited by ferocious crocodiles is invaded by a colony of rats from a passing ship. What will happen? A rat is no match for a crocodile, but there is a good chance that the rats will wipe out the crocodiles. How? By eating their eggs. Although evolution is based on the concept of survival of the fittest, we often forget that what really matters is reproductive success, not the ability to prevail in claw to claw combat.

Mammals evolved at the time when the dinosaurs began to go extinct, small rat-like creatures. It is certainly likely that some of these mammals ate dinosaur eggs, which would be enough to eradicate even the largest and fiercest of the beasts.

How did some of these monster reptiles survive (i.e., the crocodilians)? We know that some of the dinosaurs laid their eggs in nests on the ground, as fossils have been found in the Gobi desert and elsewhere. These would be the most vulnerable to predation. Crocodilians bury their eggs in sand, which is no great obstacle to modern rats and snakes but which may have provided an adequate degree of protection against more primitive mammals.

Although this is far from a conclusive argument, it seems adequate. Why is it so widely ignored (although the fact that early mammals undoubtedly ate dinosaur eggs is often referred to in texts)? Well, it isn’t a very exciting theory, and it is discouraging to think that the mighty thunder beasts were felled by a bunch of primitive rats. Clouds of iridium dust raised by a massive explosion is a lot more appealing!

Radiation

Of course there are those who like theories based on radiation that killed off the dinosaurs. This too is pretty simple. We know that the earth's magnetic field varies and even reverses from time to time. During these reversals the magnetic field must be very weak, and since it provides our shield against cosmic rays, there must have been periods of high cosmic radiation. That could certainly do some damage. However, although this hypothesis has been put forward in the literature (Reid et al. 1976 - "There is mounting evidence that past extinctions of faunal species have occurred in near coincidence with reversals in polarity of the geomagnetic field. Could the link lie in catastrophic depletions of stratospheric ozone caused by solar-proton irradiation over a reduced geomagnetic field?"), there does not appear to be any correlation between the times of geomagnetic reversals and mass extinctions.

Biblical

In the interest of fairness it should be noted that there are alternative explanations that do not require acceptance of the long time scales that palaeontologists seem to favour.

Reference

Address all correspondence to the editor, william@silvert.org. As for copyright, who would steal a simple idea? Just be sure to acknowledge the source.